Research conclusions: (1) The additional differential settlement and track irregularity meets the code requirements. The subgrade and frame bridge will rebound induced by pit excavation, and the rebound deformation will decrease after u-shape groove pouring. (2)During the whole construction process，the pit excavation is the key risk stage，the residual u-shape groove segment construction will have no effect when the pit work 72m away from high-speed railway has finished. (3)In order to reduce the influence to the existed railway and ensure the safety and comfort of railway, the railway foundation deformation influenced by pit excavation should be fully considered and limited to a small range, decrease each step excavation volume. According to reasonable procedure, independent sequential pit excavation and pouring are performed. (4) This paper provides the theoretical evidence for the construction of the adjacent high-speed railway project and also provides the valuable reference to the study on the foundation pit excavation on adjacent high-speed railway in soft soi1 area.